Document 70kjeQJRXQKvVGOn8nnd1kmK8

Cancer in relation to environmental exposure H. BOHLIG ' & E. HA1N J There are a number of difficulties involved in of asbestos mines or factories, or of ship-building mining a report on environmental asbestos-induced centres (Kiviluoto, I960; Anspach, 1962; Rubino et rmlignant tumours: at., 1968; Dalquen et at., 1970). In addition, there are regions in which the soil con O' Firstly, the term "environmental cancers" has no: yet been clearly defined. With regard to asbes tains weatherworn asbestos (Burilkov & Michailova. tos. the literature lists as "environmental cancers" 1970; Ginzburg et til., 1970) where inhabitants or workers evince in their pleura, both rndiologically tlvric which occurred in a number of widely dilfering situations, e.g., endemic, family, domiciliary, neigh and auloplically, the consequences of asbestos dust inhalation. Cases have also been observed in which bourhood. as a result of spare-time work, etc. An environmental tumour can, in the first place, be de subjects acquired plaques through contamination from occupationally exposed members of the family fined as a non-occupalional tumour; on the other (Hinz, 1968). It also seems likely that plaques may hand, the exposure itself is in many cases the same as under occupational conditions, and although it be the result of spare-time work with asbestos-con taining products. Pleural plaques must hence be may be less intensive, it is sometimes even longer looked upon as important indications in the detection lasting. Thus one can consider environmental ex posure to be simply a slighter form of occupational of environmentally jeopardised population groups (sec below). exposure, but with ill-defined borderlines (Langcr & Information concerning environmentally induced Selikoff. 1971). cancers is not entirely reliable; vet there is a series of 12) Since the cause of cancer development is still reports which prompts us to consider that many ! unknown, and since a great many individual factors tumours may be asbestos-induced, despite the ab in our environment arc considered to be conjunctly sence of an occupational exposure, hence that the I responsible for the complex canccrisation process, it is difficult to single out one group of possible agents, underlying cause must be an environmental one (Oels et a!., 1971). namely the fibriform silicates. In addition to mesothelioma of the pleura and/or While environmental asbestosis of the lungs was peritoneum the literature also mentions bronchial found to exist in animals as early as 19.10 (Stewart, carcinoma (Wagner et at. 19711. sonic of the carcin 1330: Schuster. 1931). pleuial plaques and other omas of the gastro-intcstinal tract (Merliss, 1971) pleural manifestations due to asbestos dust inhab and tumours of the hacmopoietic system as asbestos- it an in man have been recorded in the literature only induced malignant diseases: however, so far, studies dcrir.g the past 30 years (Mcunnan, 1966). There arc published in connection with environmental hazards si-me regions in which there is a high number of have nearly always been limited to a consideration of I p'aquc-heanng subjects whose asbestos dust expo mesotheliomas as sequels of asbestos dust inhalation sure is r.ot of an occupational nature hut is due to (Lielten & Pistawka, 196*). neighbourhood exposure, for example, in :hc vicinity Since the ubiquitous bronchial carcinoma is more frequently seen than is mesothelioma, evidence of its C: ic: P.2C:,''e,:;vi, Mum-rip-il llrivpi:at. SSR I u0en>ehcid, K-ilurcl ktr-jHic o:`Germany. ' C-ir'. Uepj-tmem of Chest Diseases. Municipal Hovpi- v- . Her- : .re-Herb.its. federal Republic of Germany. asbestos-induced nature in individual cases would be considerably more difficult to obtain. These car cinomas arc frequently encountered concomitantly I i 217 - r 1J tS.r ii ' it'' II I. ir' H3 i ; rs F'iw T 'a \ X BIOLOGICAL EFFECTS OF ASBESTOS with asbesiosis of the lung in asbestos workers (Demy &. Adler, 1967 ; Newhousc & Wagner, 1969), but this is far less often the case as regards mesothelioma (Elmes S Simpson, 1971), This rare tumour is found pou mortem in from 0.018 to 0.07% of all autopsies; however, following asbestos exposure, they are observed more frequently. Unlike live doseresponse relationship for bronchial cancers, a con siderably reduced lower limit for asbestos dust in halation must be assumed for mesothelioma, the magnitude of which is still open to speculation. Our information concerning the development of mesothelioma as a result of exposure to all kinds of asbestos dust is still so meagre that we can speak of causality only with reservations. However, the cor relation between asbestos exposure and consequent mesothelioma is at times so striking that there can be no doubt as to their relationship. This opens a wide field for future investigations. A noteworthy fact in connection with the occur rence of pleural plaques is that all regions which have a known increased incidence rate of mesothelioma have at the same time a greater incidence of pleural plaques. Or. the other hand, there arc areas where an increased presence of plaques has been noted where so far mesotheliomas arc absent (Kiviluolo, 1972 1)*o*r have been found only sporadically (Cartier, 1977'). In South Africa, the frequency of env ironmental mesothelioma cases is highest in the neighbourhood of the crocidolitc mines of the North-West Cape Province. In this connection, a remarkable fact is that similar observations could not be made in the vicinity of the crocidolitc mines of the Transvaal and Australia. Some cases have occasionally been found in the vicinities of asbestos processing factories in England (Newhouse & Thompson, I96J) and Ger many (Bohlig ct a!., 1970). In the past, these fac tories processed several kinds of asbestos among which, doubtless, was crocidolitc. Noteworthy numbers of cases have not so far been reported in the neighbourhoods of chrysotile, anthophvllilc. or amositc mines; although occupa tionally induced mesotheliomas were described by SelikofT (1973) in a factory processing pure amositc. A particularly striking piece of evidence is that in the neighbourhoods of shipyards in France (Tayot ct til.. 1966|. Germany (Hohlig el til.. 1970; Stosscl 1 cor'"iuni;;i!ion. ' I'cc-vOr.-I coritnunicauon. et at., 1972). The Netherlands (Stumphius. 1969), (he United Kingdom (Wagner et ol., 1971), and the USA (Tabershavv et at., 1970) environmental meso theliomas have been observed, in addition to occu pationally induced ones; thus, an increased incidence of mesotheliomas within the range of large ship building areas has been reported, the sole cause of which has up to now been considered to be pollution of the air by asbestos dust, the high concentrations of which have been demonstrated by Harries (1971). In this connection, it is important to note that since about 1900 it is precisely crocidolitc that has been used for insulation purposes in ships, particularly in war-ships (Wagner, 1968). The exact number of asbestos-induced tumours due to environmental hazards cannot be deduced from the literature, inasmuch as occupational and extra-occupational exposure can often not be separ ated with certainty on the basis of the published reports. However,' wc must reckon with a magnitude of several hundred cases, which is a sufficiently alarming number to pul us on the alert for the future. An important possible cause of asbestos-induced cancers may be found in connection with asbestos spraying as used for fire, heat, or sound insulation in ships, skyscrapers, apartment houses and car bodies Table 1. Criteria lor asbestos induced environmental cancers 1. Histology: 2. History proved by: biopsy necropsy malignant mesothelioma? bronchial carcinoma ? cucmomi of the Gl-tract? occasions for asbastos contacts: (a) endemic : asbestos mining? tod ? (b) neighbourhood: factor*#*? shipyards? asbestos spraying? (O domiciliary: family mamban \ occupationally inmates,of tha house j exposed7 (d} due to spare-time work: handing asbastos-containing products? i (e) other sources' 3. Time- { Onset of exposure al least IS years prior ! to tumour manifestations (normal latent I period - 20-40 years) 4. Ftequ*.": , . t Analogous cancers following a similar ex : posurc should bo more frequent in the respec ter# regions than in the rest of the population. 5. Evident* of asbi. es , Asbestos in tumoral tissue can but seldom be | demonstrated. Its presence m lung tktut I ought to be recorded quantitatively (for in stance following incineration) c/> --I o ro --j <o ro ro i (Lumley et at., 1971). While the asbestos sprayers a number of asbestos processing enterprises, the most themselves are nowadays completely protected by important of which is indicated on the map in fresh air supplies, others working nearby or persons Figure I. living in the neighbourhood may possibly be exposed While the incidence rite of mesothelioma among to severe air pollution resulting from the sprayed the general population of the town of Hamburg was asbestos dust. This possibility has recently led to found in 1969 to b; 0 055:.' for the past decade, the the partial prohibition of asbestos spraying in some incidence rate in the resider.fal area in the neighbour states of the USA, and in Denmark. hood of that factor;- v-as 0.96^'! The patients, who Since negative results are not considered as evi lived within the vicinity c:" the plant before the Second dence in medical diagnoses, the question arises as to World W'ar, reported that a severe, visible, snowfall how an environmental tumour may be diagnosed like air pollution was emitted from this factory, fi with certainty as being induced by asbestos dust. In which blew dust-lader. air into the atmosphere 1 Table 1 an attempt is made to compile the criteria (Dalquen et a!., 1969). required to warrant the assumption of an environ Those cases considered to be occupational tu mental tumour. These data must, however, be mours, found in former asbestos workers, were not i taken merely as a basis for discussion; point 5, in used; thus, the map shows only the 38 non-occupaparticular, indicates how much precise knowledge is lional mesotheliorr.es. Their distribution in the still lacking for the establishment of a causal relation neighbourhood cf the factory evidently seems to de ship. pend on the prevailtrg direction of the wind (Fig. 1). The number of questions still open can be demon In reference to the criteria proposed in Table 1, most strated by a discussion of the occurrence of meso of the cases shown in the figure meet at any rate theliomas in Hamburg. Hamburg is a harbour conditions 1-4. Latency times range from 20 to 48 town with an important ship-building industry and years, and medium later.: periods from 30 to 40 I years. I i Besides the cases mentioned in our preliminary report (Bohlig e:)9"0i an additional 251 proved mesotheliomas were co'lecied from the pathology departments of the lire; city hospitals, histories of which could be foe'd in 150 cases. Of these tu mours, those dee to occupational and those to i environmental causes are being mapped, and these i results will be ptcbliih.ee xs soon as possible. We feet sure that should such retrospective investi gations be made in other cities similar results would be found. We consider that investigations of this sort are necessary and should be made as soon as possible, since prospective studies in regard to this problem would come too late wherever successful dust control of the exhausted air will have rendered the neighbourhoods of the factories relatively free of asbestos dust pollution iR;ckards & Badami, 1971). Since, however, asbestos dust can also get into the atmosphere from asbestos-containing products such as brake-linings a-.i friction materials as well as Fig. t. Residence o( 38 patients sutteiing from nonoccupalionel mesothelioma due to a severe, snowfall-like asbestos air pollution in the environment ot a factory which used to blow dusi into the atmosphere during the years before World War It. from asbestos cerr.tr.'. products, it is our duty to investigate further the possibility that this indestruc tible material may accumulate in our environment, and the possible health h.zirds that this might imply. 1. i< -` . I t e GO aH ; r\j; vC f\2 U . -i? .'..rfa. ,-fjr . -~S > BIOLOGICAL EFFECTS OF ASBESTOS SUMMARY Several occurrences of cancer development following non-occupational exposure to asbestos dust are reviewed. Some discrepancies arc pointed out in reports of the appearance of pleural plaques and of malignant meso thelioma. As (he fibrous silicates form only a small fraction of environmental pollution, in which many other potential carcinogens are found, it has been difficult to establish that these fibres can be a direct causative agent of any specific neoplastic disease. A proposal is made for discriminating between asbes tos-induced cancers and those due to other causes. A survey of 38 mesothelioma cases from the neighbourhood of a single asbestos plant in Hamburg during the period 1958 to 1958 is given. REFERENCES Anspach, M. (1962) Sind Pleuras-erkalkungen palhognomonisch fur cine Asbeslosc? Internationales Archir fiir Gewerbepnthologie, 19, 10S-I20 Bohlig, H., Dabbert, A. F., Dalquen, P., Haitr, E. & Hinz, 1. (1970) Epidemiology or malignant mesotheli oma in Hamburg. A preliminary report. Environ mental Research, 3, 365-372 Burilkov, T. & Michailova, D. (1970) Asbestos content of the soil and endemic pleural asbeslosis. Enrironmental Research, 3, 443-451 Dalquen, P,, Dabbert. A. F. i. Hinz, I. 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